Adjustable workpiece mount for printing apparatus



A ril 21, 1970 c. F. FORSLUND ADJUSTABLE WORKPIECE MOUNT FOR PRINTING APPARATUS Original Filed Feb. 15. 1965 4 Sheets-Sheet 1 INVENTOR CHARLES P. FORSLUND 24M, W, M*@

ATTORNEYS April 21, 1970 c. F. FORSLUND 3,507,217

ADJUSTABLE WORKPIECE MOUNT FOR PRINTING APPARATUS 4 Sheets-Sheet 2 Original Filed Feb. 15, 1965 IINVENTOR CHARLES F. FORSLUND t E AETORNEY g April 1970 c. F. FORSLUND 3,507,217

ADJUSTABLE WORKPIECE MOUNT FOR PRINTING APPARATUS Original Filed Feb. 15, 1965 4 Sheets-Sheet s- INVBNTOR CHARLES F. FORSLUND TATTQRNES April 21, 1970 c. F. FORSLUND v ,5 7,

ADJUSTABLE WORKPIECE MOUNT FOR PRINTING APPARATUS Original Filed Feb. 15 1965 4 Sheets-Sheet 4 INVENTOR CHARLES F. FORSLUND 2; E XTTORNEYE United States Patent 3,507,217 ADJUSTABLE WORKPIECE MOUNT FOR PRINTING APPARATUS Charles F. Forslund, 3660 Lorna Vista Ave., Oakland, Calif. 94619 Original application Feb. 15, 1965, SenNo. 432,528, new

Patent No. 3,359,895, dated Dec. 26, 1967. Divided and this application Dec. 22, 1967, Ser. No. 692,993

' Int. Cl. B41f 1/38;B41l13/00 US. Cl. 101407 4 Claims ABSTRACT OF THE DISCLOSURE An adjustable workpiece holder for a screen printing apparatus, wherein controlled universal planar movement of the holder is achieved by interjoining orthogonally arranged lead screw controls mounted on the holder and a stationary reference base, providing fore and aft, side to side and rotational positioning of the workpiece.

printed parts within extremely close printing tolerances.

Still another object of the present invention is to provide a printer in which the base is constructed from a minimum number of controls which may be manipulated to easily and quickly bring the base into registration with the stencil of the printing screen.

A still further object of the present invention is to provide a printer which has accurate and flexible adjustments to accommodate operators utilizing varying printing techniques and various types of parts.

The invention possesses other objects and features of advantage, which will be set forth in the following description and drawings of the preferred form of the invention. It is to be understood, however, that variations in the description and examples may be adopted within the scope of the invention as set forth in the claims.

Referring to the drawings:

FIGURE 1 is a perspective view of the printer constructed in accordance with the present invention.

FIGURE 2 is a plan view of the device taken substantially along the plane as indicated by line 2-2 of FIGURE 1 with parts partially broken away for purposes of clarity.

FIGURE 3 is an exploded view of a portion of the device.

FIGURE 4 is a cross section of the device of FIGURE 2 shown on an enlarged scale.

FIGURE 5 is a partial cross section of a portion of the device taken substantially along the line 5-5 of FIGURE 4.

The printing device of the present invention as shown generally in FIGURE 1 consists briefly of a base 6 adapted for receiving a part 7 to be printed, a printing head 8 adapted for receiving a screen 9 and pivotally mounted on the base for movement between a lowered operative printing position in registration 'with the base ice and an elevated inoperative position, and a motor means 13 for driving various automated mechanisms of apparatus described in application Ser. No. 432,528.

A primary feature of the present invention is the ease and speed with which the part to be printed can be brought into precise registration with the stencil on the screen. Precision of registration is required in numerous types of printing, such as multi-color printing, electrical circuitry printing and particularly where the boards are printed on both sides and are electrically connected by coated perforations through the board. In the present machine, 0.001 inch repeatability is obtainable on the x and y axis. The printed areas around the perforations, known as pads must be accurately aligned in surrounding relation to the perforation.

The base in constructed of heavy, accurately machined castings and includes a workpiece holder 21 which is preferably made of ground aluminum plate and is mounted on the base for controlled side to side, fore and aft, and rotational movement in a plane for registration with a stencil on the screen when the head is in the operative position. Such displacement of the holder is effected by first manual control means connecting holder 21 and the base for movement thereof along a first axis of the plane, and second manual control means connecting the holder and the base for movement along a second axis at substantial right angles to the first axis. Base 6 is formed with a smooth surface 1 supported by upstanding legs 2, 3, 4 and 5. The holder may also be made from translucent material such as a plastic. Either the metal or the plastic may be perforated as shown by pin holes, see FIGURE 2. Where the sub-base is perforated, a member 23, formed with a chamber 24 is placed in sealing engagement with the holder 21 and attached to a vacuum line 26 for inducing a vacuum in the chamber and holding the part to be printed in close relationship with the holder. Forming a part of holder 21 is a floating frame member consisting of sides 27, 28, 29 and 30.

As best shown in FIGURES 2, 3, 4 and 5, movement of the holder is efiected by providing a pair of manually operable first lead screw members. One of the members consists of a hand knob 32 connected to a shaft 33 journaled for rotation in a bearing 34 and a sprocket wheel 36 mounted for rotation on the shaft. One end of the member is formed with a threaded portion 37. The other screw member consists of a hand operable knob 40 mounted for rotation on a shaft 38 having a threaded portion 39 journaled for rotation on the base by bearing member 41. A clutch means is associated with one of the knobs and here consists of a flange 43 providing a fric tlon plate surface and having an elongated sleeve 44 for slidable engagement on the shaft 38. Sprocket 46 is mounted for rotation on the sleeve. A friction washer 47 provides a slipping plane between flange 43 and a slip face on the sprocket wheel. The sprocket wheel is biased against the friction washer by means of a spring 48 hearing against a lock washer 49 mounted on sleeve 44. Additionally, shafts 33 and 38 are constrained against axial movement relative to base 6 by the abutment of sprocket Wheels 34, 36 and knobs 32 and 40 against sides of leg 3. A link chain 50 mounted on the sprocket wheels C0111- pletes the drive means interconnecting the manual screw members so that rotation of one turns the other. The interposition of the clutch means makes it possible for one member to be rotated while the other is stopped, or rotated at diiferent speeds or they may even be rotated in different directions.

Rotational motion of the manual knobs is translated to the holder by means of follower or nut members 51 and 52 joined to a pair of slides or slide members 53 and 54 by machine screws 56 and 57. The slide members are confined in channel grooves 58 and 59.

The slide members are connected to the floating frame of the holder by means of connecting pins 61 and 62 which interfit with openings 63 and 64 in block or bearing members 66 and 67 for pivotal rotation. With this arrangement, movement of either knob 32 or 40 moves the holder along a first axis.

Movement along a second axis at right angles to the first axis is accomplished by means of turning a second manual lead screw member consisting of a shaft 69 mounted for rotation on the holder along a line intersecting connecting pins 61 and 62, and having a threaded portion 72 and a manual operable knob 68. Shaft 69 is provided with shoulders 65 and 70 abutting opposed walls of side 28 for holding the screw member against axial movement relative thereto.

Block member 67 is formed with threaded bore 71 formed for threadable engagement with the threaded portion of shaft 69. Movement of the holder may be confined to a motion along the second axis by means of an elongated member 73 formed for receipt in bores 74 and 76 of the block members.

The unique arrangement of the parts above described makes it possible to pivot the holder by simply rotating the knobs 32 and 40 at different speeds or in different directions. Rotating knob 40 for example, and holding knob 32 immovable causes the holder to pivot about pin 61. Turning both knobs 32 and 40 at the same rate of speed, however, causes the holder to rotate at a pivot point somewhere between pins 61 and 62. Turning knobs 32 and 40 at different rates of speed in the same direction causes the holder to move in an axial direction and also to turn at the same time about a continually changing pivot point. Rotating the knobs in different directions and at dilferent rates causes the holder to rotate more rapidly about a changing pivot point. In like manner, knob 40 may be fixed and knob 32 rotated so that the holder pivots about pin 62. By rotating knob 32 at a faster rate of speed than knob 40, the sub-base pivots about a point projected toward the right of the base as shown in FIGURE 3. Thus, by varying the controls of the two knobs the base rotates about various pivot points. The holder here described has a lateral movement of about 2 inches and a front to back movement of about 2 inches. The slewing angle is about 20.

Where the sub-base is formed with a translucent sheet 21, it is sometimes desirable to light the underside of the subbase and for this purpose light bulbs 75, 77, 78 and 80 may be attached to the sub-base by brackets 79 and the light diffused by bafiler 60 and 65. The base member is provided with slots 81 and 82 to permit the insertion of electric cords 83 and 84 to pass therethrough. The base is also formed with slots 86 and 87 to permit connection of the nut numbers 51 and 52 to the slide members 53 and 54. It should be noted that the nut members are formed with projections 88 and 89 formed for sliding receipt in the slot members 86 and 87 to prevent transverse motion. Slide members 53 and 54 are held in sliding relation to the base by means of fasteners 91 and 92 inserted through slots 81 and 82 and held to the underside of the base by washers 93 and 94.

The printing head 8 consists briefly of a pair of spaced elongated arms 101 and 102 formed with openings for receiving shaft 106 for pivotal movement thereon. The arms are held in spaced apart rigid relation by a pair of cross beams, one of which beam 107 is shown in FIGURE 1.

As described in application Ser. No. 432,528 in detail, the frame for bearing the screen 9 consists of frame members 110, 111, 112 and 113. The screen is held to the cross members 107 and 108 by means of an adjustable clamp 118 having a clamping screw handle 121. The screen frame rests firmly against the printing head and thus is as rigid as the arms and cross members of the printing head. A second clamp means 122 with an adjustable knob 123 holds the screen securely in place.

The present invention is provided with means to adjust the pivotal printing head at varying distances to and above the base by a single control. Vertical adjustment of 2 inches or more may be obtained. The structural elements accomplishing the foregoing include a pair of ear bases 266 and 267 upon which is mounted a pair of upriser members 268 and 269. The right hand riser as shown in FIGURES l and '2 includes a side wall 271, front wall 272, a back wall 273 and an inner wall elongated slot 276 therein, and a top wall 277. An upstanding threaded member 286 is journaled for rotation in base 278. The upper end of threaded member 286 is journaled for rotation in upper wall 277. Nut 296 is mounted for travel on member 286 and is formed with a pin 297 connected to journal means.

Journal means are provided in reprisers 268 and 269 .and include a T-shaped member 298 having a portion formed for sliding fit in slot 276. Member 298 receiving pin 297 is formed with an upright member 306 which carries an arm 307 upon which a cam follower 308 is mounted for rotational engagement with cam 309.

Movement of theentire printing head assembly is effected by rotating hand wheel 321 connected for rotation on shaft 322, formed with a worm gear 323. Gear 324 is formed to mesh with gear 323 and is mounted for rotation on upright threaded member 286. Thus turning of hand wheel 321 rotates upright member 286 which causes nut member 296 to move in a vertical direction which in turn moves the entire printing head assembly in a vertical direction.

The journal means mounted on the left side of the machine as seen in (FIGURE 2 and enclosed in riser 268 is similar to the journal means mounted on the right side and enclosed in riser 269.

In operation, the first step is to attach the stencil in position on the screen and then the screen frame is attached to the printing head by dove-tailing clamps 118 and 122 into the matching sections of the screen frame.

The next step is to attach a holding fixture or registrating device (not shown) to the adjustable holder 21 in relation to the position of the stencil on the screen.

The next step is to register the screen to the part which consists of the steps of turning knobs 32, 40 and 68 which move the holder 21. Turning knob 32, for example, rotates shaft 33 and threaded part 37, which in turn moves threaded nut 88 along the threaded portion. Nut 51 is connected to a slide member 53 by fastener 56 which is slidably held in groove 58. A pin 61 mounted on the slide connects with a block member 66 which is connected to an elongated rod 73 connected to frame members 30 and 28 of the holder assembly. Control knob 40 is similarly connected to block 67 which is also connected to elongated member 73. Movement along the y-axis is obtained by turning knob 68 mounted for rotation in side frame 28 and threadably connected to a threaded bore in block 67. Thus when the knob 68 is turned, the entire holder assembly moves along the y-axis parallel to elongated member 73. Rotation of the holder may also be effected by turning the control knobs as more completely explained above.

After the screen is in registration with the part to be printed, the head is set for off contact printing by rotating hand wheel 321. Rotation of the wheel rotates shaft 322, which turns worm 323 which in turn moves gear 324 connected for rotation of threaded member 286. Nut 296, threadably connected to member 286 is connected to journal means 298 and moves vertically on threaded shaft 286. Shaft 106 is pivotally connected to the journal means and arms 101 and 102 are journaled on shaft 106. Thus movement of wheel 321 causes the entire printing head assembly which rests on arms 101 and 102 to pivot.

The remaining steps for preparation of the apparatus for printing relate eight adjustments of squeegee and flood bar assembly which as described in application Ser. No. 432,528 provide for application of ink or the like to screen 9, and adjustments of the electro-mechanical controls and mechanism also described in the above application providing for raising and lowering printing head 8 into registration with part 7.

I claim:

1. A floating work support for a printing apparatus comprising,

a base,

a pair of manually operable lead screw members rotatably carried by said base for rotation about fixed parallel axes of rotation extending fore and aft of said base,

a pair of follower members one each rotatably attached to each lead screw member for fore and aft movement upon rotation of said lead screw members,

a workpiece holder having a Work supporting surface and a pair of bearing members mounted below said surface and being pivotally connected to said follower members about parallel axes which are substantially perpendicular to said first named axes and said Work supporting surface, and

means guiding said bearing members on said holder for reciprocation to and from each other on a fixed line and in a plane substantially parallel to said work supporting surface whereby fore and aft and planar rotational movement of said work supporting surface is effected upon rotation of said lead screw members.

2. A support as defined in claim 1, drive means interconnecting said lead screw members for simultaneous rotation thereof upon individual manual operation of one of said lead screw members,

and clutch means releasably connecting said drive means to one of said lead screw members permitting selecfore and aft and rotational movements of said work supporting surface.

3. The support as defined in claim 1, an additional manually operable lead screw member rotatably carried by said holder for rotation about a fixed axis which is parallel to said work supporting surface nad said line of reciprocation of said bearing members, said additional lead screw member being threadably engaged with one of said bearing members to provide displacement of said Work supporting surface transversely of said first named axes.

4. A support as defined in claim 3, said base being formed with a pair of elongated guide channels extending parallel to said first named axes,

said follower members including a pair of slides mounted for reciprocation in said channels,

a pivot pin mounted on each of said slides and extending therefrom substantially perpendicularly to said plane of movement of said bearing members,

and said bearing members being formed with openings receiving said pins for journaling said bearing members thereon.

References Cited UNITED STATES PATENTS 985,857 3/1911 Thomas 10l390X 1,175,696 3/1916 Branham 101-413 1,828,771 10/1931 Flockhart 10l126 2,596,864 5/1952 Penker 10l407 X 2,729,162 1/1956 Edelberg et a1. 10l126 2,796,831 6/ 1957 Heestand 10l126 3,359,895 12/1967 Forslund 10ll23 WILLIAM B. PENN, Primary Examiner US. Cl. X.R. 10l123 

